public Connection(Neuron n, double _weight)
{
sourceNeuron = n;
parentNetwork = n.parentNetwork;
weight = _weight;
}
/// <summary>
/// Removes a neuron from the hidden layer given as absolute layernumber by parameter layer
/// </summary>
/// <param name="n"></param>
/// <param name="layer">Absolute layer number</param>
public void RemoveHiddenNeuron(Neuron n, int layer)
{
layers.ElementAt(layer).Remove(n);
}
public void AddConnection(Neuron n, double w)
{
AddConnection(new Connection(n, w));
}
public void RemoveInputNeuron(Neuron n)
{
layers.ElementAt(0).Remove(n);
}
public void RemoveOutpuNeuron(Neuron n)
{
layers.ElementAt(layers.Count - 1).Remove(n);
}
public void AddOutputNeuron(Neuron n)
{
n.parentNetwork = this;
n.name = "Output_Neuron" + layers.ElementAt(layers.Count - 1).Count.ToString();
layers.ElementAt(layers.Count - 1).Add(n);
}
public void AddHiddenNeuron(Neuron n, int layer)
{
n.parentNetwork = this;
n.name = "Hidden_Neuron_" + layer.ToString() + "_" + layers.ElementAt(layer).Count.ToString();
layers.ElementAt(layer).Add(n);
}
public void RemoveOutpuNeuron(Neuron n)
{
outputLayer.Remove(n);
}
public void RemoveHiddenNeuron(Neuron n)
{
hiddenLayer.Remove(n);
}
public void RemoveInputNeuron(Neuron n)
{
inputLayer.Remove(n);
}
public void AddHiddenNeuron(Neuron n)
{
n.parentNetwork = this;
n.name = "Hidden_Neuron" + hiddenLayer.Count.ToString();
hiddenLayer.Add(n);
}
public void AddOutputNeuron(Neuron n)
{
n.parentNetwork = this;
n.name = "Output_Neuron" + outputLayer.Count.ToString();
outputLayer.Add(n);
}
//Setup Functions
public void AddInputNeuron(Neuron n)
{
n.parentNetwork = this;
n.name = "Input_Neuron" + inputLayer.Count.ToString();
inputLayer.Add(n);
}
public static void AdjustWeights(ANN i_ANN, float[] i_DesiredOutputs)
{
if (i_ANN == null || i_DesiredOutputs == null || i_DesiredOutputs.Length != i_ANN.ANNOutputCount)
{
return;
}
// Init error gradients map (layer x neuron).
List <List <float> > layerErrorGradients = new List <List <float> >();
CommonFunctionLibrary.InitListNewElements <List <float> >(layerErrorGradients, i_ANN.layerCount);
// Iterate all layers, starting from the output one: this is a backward propagation.
for (int layerIndex = i_ANN.layerCount - 1; layerIndex >= 0; --layerIndex)
{
// Get layer and its error gradients entry.
Layer layer = i_ANN.GetLayer(layerIndex);
bool isLastLayer = (layerIndex == i_ANN.layerCount - 1);
Layer nextLayer = (isLastLayer) ? null : i_ANN.GetLayer(layerIndex + 1);
List <float> neuronErrorGradients = layerErrorGradients[layerIndex];
List <float> nextLayerNeuronErrorGradients = (isLastLayer) ? null : layerErrorGradients[layerIndex + 1];
// Iterate neuron.
for (int neuronIndex = 0; neuronIndex < layer.neuronCount; ++neuronIndex)
{
Neuron neuron = layer.GetNeuron(neuronIndex);
NeuronExecution lastNeuronExecution = neuron.lastNeuronExecution;
// Compute current error gradient.
float errorGradient = 0f;
if (isLastLayer)
{
// If this is the last layer just use iDesired - iActual.
float error = i_DesiredOutputs[neuronIndex] - lastNeuronExecution.output;
errorGradient = lastNeuronExecution.output * (1f - lastNeuronExecution.output) * error; // This is called DeltaRule (https://en.wikipedia.org/wiki/Delta_rule)
}
else
{
// If this is not the final layer, use a weighted error gradient baed on next layer error gradients.
errorGradient = lastNeuronExecution.output * (1f - lastNeuronExecution.output);
float nextLayerErrorGradientSum = 0f;
for (int nextLayerNeuronIndex = 0; nextLayerNeuronIndex < nextLayer.neuronCount; ++nextLayerNeuronIndex)
{
Neuron nextLayerNeuron = nextLayer.GetNeuron(nextLayerNeuronIndex);
float nextLayerErrorGradient = nextLayerNeuronErrorGradients[nextLayerNeuronIndex];
nextLayerErrorGradientSum += nextLayerErrorGradient * nextLayerNeuron.GetWeight(neuronIndex);
}
errorGradient *= nextLayerErrorGradientSum;
}
neuronErrorGradients.Add(errorGradient);
// Iterate over weights and adjust them.
for (int weightIndex = 0; weightIndex < neuron.inputCount; ++weightIndex)
{
float weight = neuron.GetWeight(weightIndex);
if (isLastLayer)
{
// If this is the last layer, act as do on a simple perceptron.
float error = i_DesiredOutputs[neuronIndex] - lastNeuronExecution.output;
weight = weight + i_ANN.alpha * lastNeuronExecution.GetInput(weightIndex) * error;
}
else
{
// If this is not the final layer, use error gradient as error.
weight = weight + i_ANN.alpha * lastNeuronExecution.GetInput(weightIndex) * errorGradient;
}
neuron.SetWeight(weightIndex, weight);
}
// Adjust bias as usual (keeping the learning rate).
neuron.bias = neuron.bias + i_ANN.alpha * errorGradient;
}
}
}
